A boiler used for heating or supplying hot water is a device configured to heat a desired area or supply hot water by heating water or direct water (hereinafter referred to as a “heating medium”) being heated by a heat source, and the boiler includes a burner configured to combust a mixture of a gas and air and a heat exchanger configured to transfer combustion heat of a combustion gas to the heating medium.
A boiler produced in an early on used a heat exchanger which heats a heating medium using only sensible heat generated when a burner performs a combustion operation, but a condensing boiler, which has a sensible heat exchanger configured to absorb sensible heat of a combustion gas generated in a combustion chamber, and a latent heat exchanger configured to absorb latent heat generated by condensation of water vapor contained in the combustion gas which underwent heat exchange in the sensible heat exchanger, is recently being used to improve thermal efficiency. Such a condensing boiler is being applied to an oil boiler as well as a gas boiler, thereby contributing to an increase in boiler efficiency and a reduction in fuel cost.
A prior art related to such a condensing boiler is disclosed in Korean Registered Patent No. 10-0976032. However, in the conventional condensing type gas boiler, there is a problem in that condensing efficiency is lowered, that is, thermal efficiency is lowered since heating water absorbs heat irradiated from a burner in a heat exchanger and the heat absorbed by the heating water is used to heat direct water to hot water using only a hot water heat exchanger such that a temperature of the heating water returning after heating the hot water is high.
Further, since a sensible heat exchange portion and a latent heat exchange portion are manufactured using separate heat exchange pipes, there are problems in that a unit cost of production is high and a manufacturing process is complicated.
Meanwhile, the conventional condensing type heat exchanger including a sensible heat exchanger and a latent heat exchanger is configured with a structure in which a blower, a fuel supply nozzle, and a burner are conventionally installed above a housing, and the sensible heat exchanger and the latent heat exchanger, which each have a heat exchange fin coupled to an outer side of a heat exchange tube, are sequentially installed inside the housing below the burner. However, in the conventional condensing type heat exchanger, there is a problem in that a volume of the heat exchanger is increased due to the blower being disposed above the housing and the structures of the sensible heat exchanger and the latent heat exchanger which are individually installed inside the housing.
As a prior art for improving heat exchange efficiency and minimizing a volume while resolving such a problem, Korean Registered Patent No. 10-0813807 discloses a heat exchanger configured with a burner disposed at a central portion of the heat exchanger, and a heat exchange tube wound around a circumference of the burner in the form of a coil.
The heat exchanger disclosed in the above-described Patent has problems in that a tube is deformed into a rounded shape when the tube is formed into a flat shape and a pressure is applied to a heat transfer medium portion, and a thickness of the tube becomes thick since the tube is manufactured by being rolled up.
Further, the conventional heat exchanger is configured with a structure in which a heat exchange tube is wound around a combustion chamber in the form of a coil, and a heating medium flows in only one direction along the heat exchange tube such that there is a disadvantage in which a heat transfer area cannot be widely secured since a heat exchange between a combustion gas and the heating medium is performed only in a local space formed around the heat exchanger in the form of a coil.